For studying the role of cachectin (tumor necrosis factor) in septic shock we are developing a physiological monitoring system for laboratory rats. Direct arterial pressures, temperature, respiration and cardiac output will be monitored. Special carotid/aortic catheters have been designed and tested for viability and frequency response. A novel body temperature/respiration probe is being developed for this mode. Future plans are to design and implement a four-channel computer-based monitoring system.